Some computer systems, such as servers, are commonly sold to customers without any operating system (OS) installed. Typically, the user (such as an administrator for the entity that purchased the computer system) handles installation of the desired OS at the user's site. There are a few different OS products available to such a user, and the user's options will be dictated by compatibility with the computer system itself. One might be a version of the Windows® OS such as Windows® 2003, or a version of the Linux or Novell OS. (Windows is a registered trademark of Microsoft Corporation).
To communicate with various hardware components of the computer system, OS software products typically require driver programs that are compatible with those components. For example, for the OS to successfully store data on a hard drive component of the system, the OS must have a storage driver that permits the OS to access (i.e. read and write data from and to) the hard disk drive. Often, because the development of systems and the OS proceed in parallel, the software drivers for certain hardware components of a system may not be written in time to be incorporated into the OS before it is released to the public. Thus, certain driver programs may have to be provided with the system. If these drivers are required for successful installation of the OS on the system (e.g. a disk drive storage driver), then they must be provided at the time of installation of the OS. Otherwise, the installation will be interrupted and will not complete successfully because the installation of the OS itself typically involves writing the OS program to the hard drive of the system.
Drivers critical to the installation of the OS and that have not been otherwise already incorporated into the OS may be shipped by the computer system purveyor with the computer system so that they can be provided to the OS during the OS installation process. Typically, purveyors of OS software programs build in the necessary software hooks by which these drivers may be loaded onto the system at the very beginning of the OS installation process to ensure that installation continues successfully. In Windows®, for example, the software provides a prompt during the initial stages of installation that queries the user regarding the existence of any drivers that must be loaded. If the user responds in the affirmative, OS installation is paused and drivers may be loaded by way of a CD ROM or a floppy disk via the system's CD ROM drive or its floppy drive respectively.